This study will be undertaken to determine the cause of the increased susceptibility to bacterial infection in patients with acute and chronic renal failure. Granulocytes will be isolated from normal subjects and patients with uremia and incubated in normal or uremic plasma. The vibrating reed electrometer and ionization chamber will be used to measure the oxidation of C14-labeled substrates to super 14 CO2 by the granulocytes before and after stimulation of phagocytosis with latex particles. Our preliminary studies have already demonstrated that uremic plasma inhibits phagocytosis-stimulated glucose oxidation (PSGO). We shall attempt to isolate, characterize and identify this inhibitor and to determine whether the inhibitor of PSGO is identical to any of the known uremic toxins, e.g. guanidino-succinic acid, urea, creatinine, etc. We shall also determine the effectiveness of various kinds of hemodialysis (Kolff, Kiil, Dow, hollow fiber) in removing the inhibitor from dialysis patients. Parallel studies will be carried out to determine whether the PSGO inhibitor also prevents the ingestion and/or killing of viable bacteria. In these studies pathogens commonly found in uremic patients will be incubated with granulocytes in normal or uremic plasma. The effect of the uremic plasma on bacterial phagocytosis and bacterial killing will be measured. The assay and identification of the PSGO inhibitor will allow us to devise techniques (e.g. toxin specific dialysis) for its efficient removal.